Method of and apparatus for carrying out catalytic processes



Dec. 1941. w. E. HARDING 2,255,337

METHOD OF AND APPARATUS FOR CARRYING OUT CATALYTIC PROCESSES Filed Nov.13, 1937 3 Sheets-Sheet 1 w Y *3 u. N

614,5 //VLT o vvisy on Dec. 9, 1941. w. E. HARDING 2,255,837

METHOD OF AND APPARATUS FOR CARRYING OUT CATALYTIC PROCESSES Filed Nov.15, 1957 3 Sheets-Sheet 2 Stea [r 9 aha/vibe I Dec. 9, 1941. 'w. E.HARDING 2,265,837

METHOD OF AND APPARATUS FOR CARRYING OUT CATALYTIC PROCESSES Filed Nov.13, 1937 3 Sheets-Sheet 3 Patented Dec. 9, 1941 ATENT OFFICE METHOD OFAND APPARATUS FOR CARRY- ING OUT CATALYTIC PROCESSES ration of DelawareApplication November 13, 1937, Serial No. 174,429

4 Claims.

This invention relates to a method of and apparatus for carrying outcatalytic reactions which require regeneration of the catalyst torestore its activity and pertains more particularly to a method andapparatus which will permit the process to be carried out continuouslyas distinguished from intermittent processes in which the reaction andregeneration is accomplished in cycles of these two alternatingoperations.

While this invention in some of its broader aspects will have a moregeneral application, it is of particular advantage for catalytictreatment of hydrocarbons, such as catalytic cracking andpolymerization.

It has heretofore been discovered that cracking oil in the presence ofcertain types of adsorptive catalysts such as naturally active clays orclays made active by acid or other suitable treatment and certain typesof synthetic gels results in the production of gasoline having highanti-knock properties. However, during the cracking operation, theactivity of the catalyst is rapidly reduced due to the formation ofsolid carbonaceous deposits on the surface of the catalyst.

In'order to restore the activity of the catalyst, it becomes necessaryto periodically remove the carbonaceous deposits so formed. The removalcan be effectively accomplished by burning the catalyst with anoxidizing gas such as air or a mixture of air and steam.

According to one mode of operation heretofore proposed the regenerationis carried out within the same chamber in which the crackingisaccomplished in alternate cracking and regenerating steps. In order tooperate sucha process continuously, it is necessary to provide aplurality of reaction chambers with manifold lines so that any one ormore. of the reaction chambers may be operating on the cracking streamwhile the remainder are undergoing regeneration.

In addition to the actual time required for regeneration, there is afurther substantial time loss between the cracking and regeneratingsteps and vice versa, necessary to condition the catalyst bed. Forexample, after the cracking has been discontinued and before theregeneration is begun, it is necessary to remove volatile oilconstituents absorbed by the catalyst to prevent possible explosionsresulting from contacting the hot volatile oil with the regeneratinggas. This may be accomplished by steaming the catalyst to vaporize theoil. Following the regeneration,

it is also desirable to steam-the catalyst to remove oxygen or otherproducts of regeneration before returning the catalyst chamber to thecracking stream. Moreover, the cracking and regenerating steps mayoperate at different temperature levels which requires additional timeto bring the catalyst to the required temperatures between the steps.

For these and other reasons, such an intermittent cracking processrequires additional reaction chambers over'that required if crackingcould be carried out continuously without interruption for regeneration.

In addition to the intermittent cracking and regeneration processheretofore mentioned, it has also been suggested to continuously removespent catalyst from the reaction chamber and regenerate the same outsidethe reaction chamber and continuously introduce spent and fresh catalystwithout interrupting the cracking. For example,

it has been suggested to suspend the catalyst in finely divided form inthe vapors to be cracked during their passage through the reactionchamber and subsequently separating the vapors from the catalyst. Inorder to efiectively separate the catalyst from the vapors, expensiveseparating equipment is required and it is difiicult to properly controlthe time of contact between the vapors and the catalyst.

One of the importantobjects of the present invention is to provide aprocess for carrying out catalytic cracking and polymerization and otheranalogous chemical reactions in a continuous manner.

Another important object of this invention is to provide a continuousprocess for catalytically cracking oil which will require a smalleramount of equipment for a given capacity and which will reduceinstallation and operating costs.

Another important object of this invention is to provide a continuousprocess for the catalytic cracking of oil which will permit a moreaccurate control of contact time between the oil vapors to be crackedand the catalyst bed.

A further object of the invention is to provide an improved apparatusfor catalytic cracking and other similar catalytic reactions in which itis necessary to regenerate the catalyst frequently.

A further object of the invention is to provide an apparatus forcatalytic conversion which will permit more effective control of thecracking conditions.

Other more specific objects of my invention will become apparent fromthe more detailed objects.

In accordance with the broader phases of my invention, the catalyst bedis caused to pass progressively through the reaction zone in a solidrelatively compact form, at any desired rate of speed. According to themore specific aspects of the invention, the catalyst mass in relativelycompact form is conveyed through the reaction zone at any'desired rateof speed and the vapors to be reacted pass through a uniform depth ofcatalyst mass and in a direction transverse to the general direction ofmovement of the catalyst mass. According to further phases ofmy'invention the catalyst mass is conveyed through the catalytic zone,then subjected to conditioning and regenerating equipment in which theactivity of the catalyst is restored and is then returned to thecatalytic chamber in a continuous manner.

Various other objects and. advantages of the invention will be apparentfrom the more detailed description hereinafter, in which reference willbe made to the accompanying drawings.

In the drawings, Figure 1 is a side view of a battery of catalyticreaction chambers constructed in accordance with the invention showingparts in section and conveyors for introducing and removing catalysts toand from the chambers.

' Figure 2 is a continuation of Figure 1, showing diagrammatically asystem for treating and regenerating the catalyst and for the recoveryof reaction products, and Figure 3 is a sectional view of the catalyticreaction chambers shown in Figure 1.

Referring to Figure 1, the numeral ill indicates a charging line forintroducing the gases to be reacted into a bank of catalytic chambers H.To this end, the charging line Ill is provided with separate branchlines l2 provided with valves I3 leading to each of the catalyticchambers H. The reaction chambers ll shown in Figure 1, are all of thesame construction, so that a description of one of the chambers willsuffice forl all. 4 a l |.i.-:r Referring to Figure 3, the catalystchambers ll comprise an inner metallic shell l4 having perforations Maand an outer spaced concentric shell IS. The space between the inner andouter shells l4 and 15 forms a vapor space for the collection of vaporsremoved from the catalyst ill) zone. The outer shell I5 is lagged withsuitable insulating material to reduce radiation losses. Extendingdownwardly through a stufilng box 16 in the top of the inner shell 14 isa central hollow shaft I! having perforations Ila. terminating in athrust bearing l8 supported at the bottom of the inner shell I4. Thehollow shaft I1 is provided with suitable means for effecting rotationthereof, such as a pinion gear l9 located at the top thereof. Branchlines I2 leading from the charging line 10 are connected with the rotaryshaft H at the upper end thereof through a suitable stufling box 2| toprovide a sealed communication between the branch lines l2 and thehollow shaft I'l so that the gases to be reacted are introduced into thereaction chamber through cured to the rotary shaft 1! and forceddownwardly through the reaction zone. 'As shown in Figure 3, the upperconvolution of the spiral flange 22 is of greater pitch than the otherconvolutions so that the catalyst is slightly compressed and moreuniformly distributed throughout the full cross-sectional area of thecatalyst zone before being introduced into the main treating section ofthe reaction zone.

The vapors introduced into the reactionchamher through the rotary shaftI! pass through perforations therein into the bed of catalyst movingthrough the reaction zone and the reacting gases are caused to passtransversely through the catalyst bed and are exhausted throughapertures in the inner shell H. The reaction products after passingthrough the apertures are collected in the annular chamber formed by theinner shell and outer shells H and IS. The reacted gases are withdrawnfrom the annular chamber through a plurality of outlet portscommunicating with pipes 26 at the bottom of the chamber. The pipes 26connect at the outer ends with a bustle pipe 21 extendingcircumferentially of the reaction chamber H. The bustle pipe 21 in turnconnects through a line 28 provided with a valve 29 to a manifold line3| through which the reaction gases are caused to pass to a suitablerecovery system, such as a fractionating tower 32 (as shown in Figure 2)for separation of the desired products from the reaction gases. 1

As shown in Figure 3, the perforations in th inner shell II and in therotary shaft H begin below the second convolution of the spiral flange22 so that the upper section between the first and second convolutionsof the spiral flange 22 does not form a part of the reacting section ofthe chamber ii. The space between the first and second convolutionsforms a charging zone for the catalyst. By providing a greater pitch tothe first convolution of the flange 22 the catalyst upon passing to thesecond convolution of the flange is forced into a smaller space and thustends to flll any voids which may result from unequal charging of thecatalyst, so that the catalyst may be uniformly distributed throughoutthe full cross sectional area of the reaction zone before coming incontact with the gases to be reacted.

The apertures in the rotary shaft l1 and in the inner shell l4 may be ofuniform size and spaced throughout the full length of the react ingsection of the chamber l I as above described, or the size and spacingof the apertures may be graded to control the amount of the reactionproducts passing through different vertical sections of the reactionchamber. For example, as the catalyst progresses through the reactionzone its activity gradually becomes reduced due to formation ofcarbonaceous deposits. These carbonaceous deposits, however, increasethe density of the catalyst mass and hence the resistance of thecatalyst to the flow of gases therethrough. As a. consequence, when theapertures are of uniform size and spacing, a relatively larger pro-.portion of gaseswill pass through the fresher catalyst per unit time.In this respect, my invention provides a more or less self compensatingmethod of carrying out the treatment in that the time of control willvary inversely with the activity of the catalyst and thus tend to causeuniform conversion of the oil throughout the fulllength of the catalystzone. However, the size of the apertures and the spacing therebetweenmay be so adjusted so as to cause more or less of the vapors to passthrough the top and bottom of' the reaction zone as desired. Moreover,the pitch of the spiral flange passing through the catalyst zone may begradually increased from top to bottom to compensate for increase involume of catalyst due to formation of carbonaceous deposits so that thepressure,

drop through the catalyst bed is substantially uniform throughout thefull length thereof. From the above, it will be noted that the volume ofvapors passing through the different vertical sections of the catalystzone may be controlled as desired by modifying the size and spacing ofthe apertures and the pitch of the spiral flange 22.

As shown in Figur 3, the apertures both in the rotary shaft l1 and inthe inner shell I4, may be inclined to reduce plugging of the apertureswith catalyst material.

The catalyst, after passing through the reaction zone, is withdrawn fromthe bottom of the chamber through line 32 leading to a common screwconveyor 33 adapted to receive catalysts from each of the reactionzones. The screw conveyor 33 is adapted to convey the catalyst to asuitable recovery apparatus, illustrated diagrammatically in Figure 2,for the treatment and regeneration of the catalyst.

The catalyst, after being reactivated, is returned to the reactionchambers through a suitable conveyor, such as a screw conveyor 34 whichdischarges the catalyst through branch pipes 35 into the hoppers 24.Positioned in the outlet line 32 for withdrawal of catalyst from thereaction chambers and the branch lines 35 for introducing the freshcatalyst into the hoppers 24, are suitable means for maintaining adifferential pressure between the catalyst chamber and the conveyors '33and 34. Any suitable pressure seal may be provided in these lines. Asshown at the bottom. of Figure 3, the pressure seal may comprise arotary valve 33 coupled with a reciprocating valve, having two spacedplungers 38 and 33 adapted to reciprocate within a cylinder 4| and forma seal between the conveyor line 33 and the reaction chamber. Thecylinder 4| communicates by means of line 42 leading to the conveyor 33from which the catalyst is passed to a suitable regenerating system. Theplungers 33 and 39 are secured to a piston rod 43 operated by suitablereciprocating mechanism, such as a hydraulic piston 44. The plungers 38and 39 are so spaced on the piston rod 43 that when the piston rod is inthe extreme forward position, the plunger 38 extends beyond the outletpipe 42 and the plunger 39 is positioned between the inlet and outletports of the cylindrical section 4|. When the piston rod 43 is in aretracted position, the advanced plunger 38 is positioned between theinlet and outlet ports of the cylindrical section 4| so that in eitherposition of the plungers there is a seal between the conveyor 33 and theoutlet line 32. The rotary valve 36 is operated to close communicationbetween the outlet line 32 and the cylindrical section 4| duringoperation of the plungers 38 and 39.

Pressure seals of similar construction are provided in branch linesleading from the charging conveyor 34 to the hopper 24 for each reactionchamber.

By providing pressure seals in the inlet and outlet of each reactionchamber, as above described, any desired pressure may be maintainedwithin th reaction chambers or any one or more of the chambers may bewithdrawn from operation without interrupting operation of the remainingchambers. For example, by closing any one or more of inlet valves l3 inbranch lines l2 and outlet valves 29 leading from the bustle pipe 26 tothe manifold 3| and the rotary valves in branch lines 23, any desirednumber of reaction chambers may be withdrawn from operation. Rotaryvalves 36 in the outlet of the chambers withdrawn from operation may becontinued to operate until the catalyst has been completely removedfrom. the chamber after which the chambers may be inspected or repaired.

The invention will now be described with reference to the cracking ofhydrocarbon oils, it being understood that in its broader aspects itwill have a more general application.

The oil to be cracked is first vaporized in a suitable heating unit, notshown, and heated to the desired reaction temperature, after which it isintroduced into the system through line Ill of Figure 1. The heatedvapors introduced through line III are passed through any one or more ofthe branch lines |2 to the central hollow rotary shaft in the reactionchamber The heated vapors thence pass through the apertures in thehollow shaft into contact with the catalyst, and pass through thecatalyst bed in a direction transverse to the direction of the generalmovement of the catalyst through the reaction zone. The rate of flow ofthe oil vapors and the capacity of the reaction zone are controlled toprovide the desired reaction time within the zone. The reactionproducts, after passing through the catalyst material, pass from thecatalyst bed through apertures in the inner'shell |4 into the annularvapor space surrounding the inner shell. By introducing the gases intothe upper end of the rotary shaft and withdrawing the vapors from thebottom of the annular chamber all of the gases have substantially thesame length of travel within the reaction chamber II from the point ofentry to the point of withdrawal.

The reaction products are withdrawn from the annular chamber throughpipes 26 and are collected in the bustl pipe 26 from whence they passthrough lines 28 to a manifold line 3| leading to a fractionating tower32 The gases, during their passage through the fractionating tower 32,are subjected to fractional condensation to condense constituentsinsufilciently cracked to motor fuel as condensate. The total condensateformed in the fractionating tower 32 may be withdrawn from the bottom.therefrom through line 5| or the fractionating tower may be providedwith any desired number of trap out trays 52 for separately collectingindividual fractions formed in the fractionating tower. For example,when recycling insufiiciently cracked condensate to the cracking unit,it is sometimes desirable to recycle only a lighter fraction of thecondensate and to separately withdraw from the system the highestboiling condensate formed. In such cases, the trap out trays 52 may bepositioned to collect the desired condensate for recycling to thecracking unit and the collected condensate may be withdrawn through line53 and recycled to the cracking zone through a line (not shown).

Vapors remaining uncondensed in the fractionating tower 32a passoverhead through line 54 to a condenser 55 in which the desireddistillate product is condensed. Products from the condenser 55 pass toa receiver 56 in which the liquid distillate separates from the normallygaseous constituents. The distillate is withdrawn from the receiver 56through line 51 and the gaseous constituents are vented from the systemthrough line 58 provided with valve 59 for maintaining the desired backpressure on the cracking equipment. The distillate withdrawn throughline 51 may be subjected to any desired further treatment for conversioninto the final stabilized gasoline product.

The catalyst employed during the cracking operation may be any of thecracking catalysts, such as solid adsorptive contact material, forexample, active or activated clays, such as fullers earth oracid-treated bentonitic clays or synthetic gels. The catalyst may be inmolded or finely divided form or deposited on a suitable inert carrier.

The activity of the catalyst within the reaction chamber is rapidlyreduced due to the formation of carbonaceous deposits resulting from thecracking treatment. The movement of the catalyst through the reactionchamber is controlled by regulation of the speed of rotation of theshaft I 1, so that the activity of the catalyst emerging from the bottomof the reaction zone is such that further treatment therewith is nolonger desirable. The spent catalyst is then removed from the zonethrough the line 32 and conveyed by means of a screw conveyor 33 to a 3steaming chamber 6| in which the spent catalyst is subjected todistillation to remove volatile oily constituents from the surface ofthe catalyst. After being subjected to the desired steaming treatment,the catalyst is removed from the chamber BI and introduced into asuitable regenerating chamber 63 in which the carbonaceous deposits onthe catalyst are removed. The regeneration of the catalyst may beaccomplished effectively by passage of an oxidizing medium, such as airor air diluted with steam, to burn off the carbonaceous deposits.Theregeneratlng equipment may take a number of different forms andconstitutes no part of the present invention. It is shown in thedrawings only schematically. When regenerating catalysts, such asactivated clays, it is desirable to accurately control the temperatureof regeneration in order not to permanently reduce the activity of thecatalyst. Any regenerating mechanism capable of effecting closetemperature control over the catalyst during regeneration can be used.For example, the catalyst may be introduced into a conventionalHerreshofi type of furnace in which the catalyst is causedto passdownwardly over a plurality of vertically spaced hearts incountercurrent contact with hot oxidizing gases. The catalyst may beconveyed from one hearth to the other by the conventional rabble armsmounted on a rotary shaft within the furnace.

In addition to the Herreshoff type of furnace for effectingregeneration, the conventional type of sintering apparatus adapted forsintering low grades ores may be employed satisfactorily. This type ofapparatus comprises generally a travelling grate conveyor passingthrough a combustion zone in which the air or oxidizing gas is passedthrough the grate for burning-the material thereon. This type ofapparatus is well adapted for controlling regeneration of the catalystssince the catalyst layer on the grate conveyor may be at any desireddepth to efiect close control of the combustion temperature. Thesesintering devices are commonly known in passed through a conventionalrotary kiln through which the oxidizing gases are caused to pass. Theregenerating mechanism is preferably a continuous one, wherein thecatalyst may be continuously introduced and removed from theregenerating zone.

The regenerating catalyst, after withdrawal from the regenerating zone,is again introduced into a steaming zone which is indicated on thedrawings as chamber 65, wherein the catalyst is subjected todistillation to-remove regenerating gases from the surface thereof. Thissecond steaming operation may be dispensed with if desired. The catalystmay then be passed from the chamber 64 to the screw conveyor 34 employedfor conveying the catalyst to the hoppers 24 of the individual reactionchambers II. The hoppers 24 are of sufiicient capacity so as to providea-suflicient reserve supply of catalyst to permit the catalyst to beintroduced into the individual reaction chambers at a uniform rate.

In the drawings, there is shown common con veyors for introducing andremoving the catalyst to a bank of reaction chambers. It will beunderstood that the speed of the common charging conveyor 34 and thecommon discharging con- ,veyor 33 may be synchronized so that thecatalyst is charged and discharged from'each chamber at the same rate.Moreover, the driving gear for the rotary shafts I! in the reactionchambers may be operated independently or syneh i sothat all operate atthe same speed. Also, the dllvmg ears for the rotary shaft l! arepreferably synchronized with the catalyst charging and dischargingvalves 25 and 35 so that the rate of charging and discharging is variedautomatically with variations in speed of rotation of the shafts H.

While I have shown common conveyors 33 and 34 for discharging andcharging a bank of reaction chambers, it will be understood thatseparate conveyors may be employed for each reaction chamber or that asingle reaction chamber may be used instead of a bank in accordance withcertain phases of the invention.

Having described the preferred embodiment of the invention, it isunderstood that it embraces such other variations and modifications ascome within the spirit and scope thereof.

In the accompanying claims, it is my intention to cover the invention asbroadly as the art will permit.

I claim:

1. In the catalytic cracking of petroleum oil to produce motor fuel ofhigh anti-knock properties wherein the oil to be cracked is passed invapor form through a reaction zone containing a bed of crackingcatalyst; the improvement which comprises progressively passing the bedof catalyst through the reaction zone and passing the oil vapors throughsaid bed of catalyst in a direction transverse to the general directionof movement of catalyst through the reaction zone.

2. An apparatus for carrying out vapor phase catalytic reactions whichcomprises a metal shell forming a reaction chamber adapted to contain abed of catalyst material having perforations in the side walls thereof,an outer jacket in spaced relation to the side walls of said reactionchamber forming an annular enclosed space surrounding said reactionchamber, a perforated conduit extending longitudinally within saidreaction chamber in spaced relation to the walls thereof, means integralwith said conduit for moving the catalyst through the reaction zone,means communicating with said perforated conduit for introducing gasesto be reacted and means communicating with said annular space forwithdrawing reaction products.

3. An apparatus adapted to carry out vapor phase catalytic reactionscomprising a reaction chamber adapted to contain a bed of catalysthaving perforated side walls, a jacket surrounding said side walls inspaced relation therewith to form an annular chamber in vaporcommunication with said reaction chamber, a perforated conduit extendinglongitudinally within said reaction chamber, means for rotating saidconduit, a spiral flange secured to said conduit\adapted to move saidbed of catalyst through the reaction chamber during rotation of saidconduit, means for continuously charging said reaction chamber withcatalyst, means for continuously removing catalyst from said chamber,means communicating with said perforated conduit for introducing vaporsto be reacted and means communicating with said annular space forremoval of reaction products.

4. In an apparatus for contacting vapor with.

solid catalyst material, a chamber comprising a perforated tubularshell, a tubular jacket in spaced relationship thereto forming anannular space surrounding said chamber, a driven member comprising ahollowperforated shaft disposed substantially concentrically withrespect to said chamber, a spiral flange integral with said drivenmember comprising a catalyst conveying means and extending substantiallythe entire length of the shaft within said chamber, means for supplyinga solid catalytic material to the reaction chamber at or near the top ofsaid conveying means, means for introducing vapors into said hollowperforated shaft for conductance through the conveying means andseparate means for recovering the catalytic mass and the vaporsrespectively which have passed from the reaction chamber.

WILLIAM E. HARDING.

